How much will the damages in Syria cost after the gas attack?

Answer 1

There are two issues here that make this question unanswerable:

1. Gas attacks by there nature do little to no physical damage to buildings or infrastructure; they simply kill people.
2. One cannot put a price tag on loss of life.

What light be more easily quantified, by future historians who tally the final costs, is the price tag of World War 3 that fires up after the US unilaterally strikes targets in the heart of one of Hezbollah's allies.